LM3875 amp problem

sebtdi · 10th July 2007, 09:38 PM

Hello

I just finished building the Audiosector Lm3875 dual mono kit as a standalone amplifier. I have a problem with the gain being 2-3x stronger on the right channel than the left.

Did I screwed up something during the installation? everything looks normal to me. I use the chip amp with a tube pre.

Thanks

drummer_Dave · 10th July 2007, 11:07 PM

can you take some pictures of the circuit boards close up? top and bottoms, linking the schematic would also help

Dave

AndrewT · 11th July 2007, 12:01 PM

Hi,
is that a resistor soldered to the earth terminal on the mains input socket?

Where is the mains safety earth?

sebtdi · 11th July 2007, 02:06 PM

Quote:

Originally posted by AndrewT
Hi,
is that a resistor soldered to the earth terminal on the mains input socket?

Where is the mains safety earth?

The resistor connected to earth is 10R. I have used a star ground configuration for signal ground, output ground, Pg+,PG-. The chassis is not grounded to earth.

AndrewT · 11th July 2007, 02:21 PM

Hi,
are your safety rules different from the UK?
We are required to connect all exposed conductive parts to safety earth.

sebtdi · 12th July 2007, 03:56 AM

Anybody?

Dxvideo · 12th July 2007, 07:23 AM

Dear sebtdi,

Is your enclosure a handmade one? Did you design and made it or a ready one?
I know its not connected with your matter but I've seen that case some places and wonder if its for sale in somwhere..

Thx.

11th July 2007, 12:01 PM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, is that a resistor soldered to the earth terminal on the mains input socket? Where is the mains safety earth? __________________ regards Andrew T.

11th July 2007, 02:21 PM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, are your safety rules different from the UK? We are required to connect all exposed conductive parts to safety earth. __________________ regards Andrew T.

12th July 2007, 07:23 AM	#7
Dxvideo diyAudio Member Join Date: Nov 2003 Location: Turkey	Dear sebtdi, Is your enclosure a handmade one? Did you design and made it or a ready one? I know its not connected with your matter but I've seen that case some places and wonder if its for sale in somwhere.. Thx. __________________ Best regards, Ozgur

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10th July 2007, 11:07 PM	#2
drummer_Dave diyAudio Member Join Date: Oct 2006	can you take some pictures of the circuit boards close up? top and bottoms, linking the schematic would also help Dave

12th July 2007, 03:56 AM	#6
sebtdi diyAudio Member Join Date: Jun 2007	Anybody?

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